Regenerative air and gas preheater



F. LJUNGSTROM E-r'AL REGENERATIVE AIR AND GAS PREHEATER Filed Aug. 3; 1922 4 Sheets-Sheet 2 1,63 ,5 1927' F. LJUNGSTROM ET AL 8 39 REGENERATIVE AIR AND GAS PREHEATEH F iled Aug- 5. 1922 4 Sheets-Sheet 3 A 19.7 1638539 8 2 F. LJUNGSTROM ET AL KEGENERATIVE AIR AND GAS PREHEATER Filed Aug- 3. 1922 4 Sheetg-Sheet '4 INVENTORS 1 LjWcTrofm BYMEFflnJemsmz 4 v r l ATTORNEYS.

Patented Aug. 9, 1927.

u ITED s 1,638,539 F Fl C E FREDRIK LJUNGSTRGM, OF LIDINGO-BREVIK, AND NILS FREDRIK FILEMON AN- DERSSON, OF STOCKHOLM, SWEDEN, ASSIGNORS TO AKTIEBQLAGET LJUNGSTRbMS ANGTUBBIN, 0F STOGKHOLM, SWEDEN, A CORPORATION.

REGENERATIVE AIR AND GAS PREHEATER.

Application filed August 3, 1922. Serial No. 579,528, and in Sweden November 21, 1921.

A regenerative air preheater has previous ly been suggested in which a rotor containing a regenerative material rotates on the one hand in waste gases and on the other hand in air or gas to be heated, the gases and the air passing through the rotor. According to the prior suggestions said rotor was enclosed by a separate casing supporting fans and their driving device and constituting chambers or channels for the air and the gases. Such preheaters are adapted to be placed near a steam boiler outside the chimney and to be connected with conduits leading to the chimney and the furnace.

In many cases it has, however proved ditficult, particularly in marine plants, to make room for such an air preheater, owing to the space around the boiler being generally very limited. It being however of importance that the preheater be situated near the steam boiler so as to obtain short gas and air conduits, the preheater could not be placed in the open air, for instance above the stokehold, because of the difiiculty consisting in using the much colder outer air for the preheating instead of the warmer air in the'stokehold. On account thereof the location of such a preheaterinduces great inconveniences.

The objectof the invention is to make place for the air preheatcr near the steam boiler and at the same time to obtain shortconduits to the furnace and the stokehold.

To this purpose the invention consists in placing the rotor inside the stack which is divided wholly or partly into a channel'for the waste gases and a channel for the air or other gas to be heated, the casing enclosing the rotor being connected with the wall or shell of the stack or constituting the same.

Several embodiments of the invention are illustrated in the accompanying drawings showing a marine boiler plant provided with an air preheater of regenerative type placed in the stack of the steam boiler.

Fig. 1 shows an embodiment of the plant viewed in the direction towards the furnace openings of the boiler and Fig. 2 a side view of the plant. Fig. 3 is a view similar to Fig. 1 and showing another embodiment, Fig. t a side view, Fig. 5 a cross-section on line 55 in Fig. 4 and Fig. 6 is a plan view of xthe rotor with the stack surrounding the.

Referring to Figs. 1 and 2, 1 designates a marine steam boiler the smoke box of which is located at the firing end of the steam boiler, the stack 5 therefore being also situated at the same side of the steam boiler. Placed in the lower part of the stack 5 is the rotor 6 of an air-preheater of the type described and illustrated in the co-pending applications of Fredrik Ljungstrom filed April 1l, 1921, Serial No. 460600, and filed August 3, 1922, Serial No. 579544 and adapted in known manner to be removed in radial direction. The rotor is actuated by, means of a driving device 7 also used for fans 8 and 11. According to the invention the stack 5 is divided into two channels, one 8 for the waste gases and one 9, 9 9 for the air, the rotor 6 being so arranged that it rotates through both of said channels. Besides the stack5 is so constructed that its wall or shell forms a casing around the rotor The waste gases of the steam boiler pass from the smoke box 4 into the channel 8 and through the rotor 6 to a chamber 8 above the rotor, from which the waste gases are forced upwards by means of one or more fans 8 through an elbow pipe 8 preferably ending in a difiuser 8 to a part of the stack 5 situated above the rotor. The fresh air in the space 10 around the boiler is sucked in by one or more fans 11 and issues into a chamber 9 above the rotor, the elbow pipe 8 of the waste gases passing through said chamber. After having passed through the rotor 6 and having been heated by such passage, the air enters a chamber 9 beneath the rotor and is then conducted through a channel 9 conveying the air to the furnaces 2 and 3. Theoutlet channel 9 of the heated air leading from the air preheater is located in part in the channel 8 of the waste gases and in part in the smoke box 4:, the air thus being surrounded everywhere by a warmer medium and consequently not only protected against cooling but also further heated according to the counter-flow principle.

The air channels are provided in known manner with dampers controlling the air current and consequently also the furnace draught, this object however also being attainable by increasing or decreasing the work of the fans. The fans are actuated by a separate driving machine, for instance a small steam turbine 12, located in the space "near the chimney. Said turbine actuates the shaft of the fans for instance directly by belt transmission or the like the speed nec'-- essary for actuating the rotor being reduced from said shaft, according to earlier sugges or adjustment.

In the embodiment shown in the Figures 3 to 6 inclusive the Waste gases are capable of passing from the smoke box past the rotor'to the stack, the rotor or the casing ,enclosing the preheater forming one or more channels or being provided with such channels for the waste gases, through which channels the latter, if desired, can pass past the regenerative. material of the rotor directly to the stack.

In Figures 3 to 6 13 designates the steam boilers, 14 their common stack, 15 the smoke box and 16 the furnaces of the steam boilers.

In the lower part of the stack 14 a regenerative air preheater 1'? of known construction is placed and actuated by a separate engine or shaft 18. 19 and 20 designate two fans sucking in the air in the direction of the arrow 21 and blowing 0d the waste gases to the stack in the direction of the arrow 22 respectively.

In order that the waste gases, as stated above, may be capable, if desired, of passing past the rotor to the stack, the rotor 23 is provided with one or more channels or passages, -preferably, as shown in the drawing, with one central channel 24 through which the waste gases can pass without passing the regenerative material placed in the peripheral part of the rotor surrounding the channel 24:. In conformity thereto the vcasing 25 surrounding the air preheater 17 and the rotor 23 respectively and, as stated above, preferably formed by the wall of the stack is divided into channels, one peripheral channel 27and one central channel 26, both of these channels being provided for the waste gases, and one channel 28 for the preheated air. The peripheral channel 2? is only to. be used when the waste gases pass through the regenerative material of the rotor which regenerative material is indicated at. 35 and consists preferably as shown of" alternate corrugated and substantially straight plates thus giving a plurality of vertical passages through the rotor, it being however, understood the many forms of regenerated material may be and the co-pending applications.

channel 26 is only to be used, when the waste disclosed, being the sole invention of Fredrik Ljungstrom, is not claimed herein but is reserved as the claimed subject matter of other The present invention is obviously independent of the construction and arrangement of regenerative material used.

To cause the waste gases to pass alternately through said peripheral and central channels dampers 32 are provided in the stack and adapted, when reversed, to conduct the waste gases in either direction.

The preheated air flows from the air preheater through the channel between the steam boilers 15 to the distributing pipe 30 through which the air is conducted in known manner to'the furnaces. In case of a small distance between the steam boilers the channel 29 may be constructed as a receptacle 31 placed between the boilers.

An air preheater according to the invention does not require any enlarged space but may be arranged in marine plants not adapt ed from the beginning to such a. device. It is of no significance in what place the rotor of the preheater is located in the stack; preferably, however, it is to be placed as near the steam boiler as possible.

What we claim as new and desire to secure by Letters Patent of the .United States is 1. In a marine boiler plant, the combination with a boiler and a stack leading vertically therefrom; of a channel for air leading to said boiler and a channel for flue gases leading from said boiler, said channels lying partly within said stack, a regenerative air'preheater comprising a mass of regenerative material having passages through the same for air and flue gases, means for causing relative motion between said channels and said mass, a casing around said mass forming a section of said stack, a second casing forming a section of said stack above said preheater, said last named casing having an aperture therein and being divided to form the inlet for said air channel and a portion of said flue gas channel, a fan located in said inlet aperture, a fan located within the flue gas channel within said last-named casing, and means for driving said fans.

2. In a marine boiler plant, the combination. with a boiler and a stack leadingverice tically therefrom; of a channel for air and a channel for flue gases, said channels being partly arranged in said stack, a regenerative air preheater comprising a rotor containing regenerative material provided with passages through the same for air and flue gases, said rotor being arranged to rotate in said channelsand'about a vertical axis, a cylindrical casing surrounding said rotor and forming a section of said stack, a second casing located above said rotor and forming a section of said stack, said last named casing having an aperture therein and being divided to form the inlet for said air channel and a portion of said flue gas channel, a fan located in said inlet, a fan located in the flue gas channel within said last named casing, and means for driving said fans and rotor.

3. In a marine boiler plant, the combination with a boiler and a stack leading vertically therefrom; of a channel for air and a channel for flue gases, said channels being partly arranged in said stack, a regenerative air preheater comprising a rotor containing regenerative material provided with p passages through the same for air and flue gases, said rotor being arranged to rotate in said channels and about a vertical axis, a cylindrical casing surrounding said rotor and forming a section of said stack, a second casing located above said rotor and forming a section of said stack, said last named casing having an aperturetherein and being divided to form the inlet for said air channel and afportion of said flue gas channel, a drive shaft mounted transversely ofsaid casing, a fan mounted on said shaft in said inlet aperture, a fan mounted on said shaft in said flue gas channel, and means for driving said shaft and rotor.

4. In a marine boiler plant, the combination with a boiler and a stack leading vertically therefrom; of a channel for air and a channel for flue gases, said channels being partly arranged in said stack, a regenerative air preheater comprising a rotor containing regenerative material provided with passages through the same for air and flue gases, said rotor being arranged to rotate in said channels and about a vertical axis, a cylindrical casing surrounding said rotor and forming a section of said stack, a second casing located above said rotor and forming a section of said stack, said last named casing having a vertically poslted aperture therein and being divided to form the inlet for said air channel, and a portion of said flue gas channel, means dividing the flue gas channel in said casing into two sections and having a vertically posited opening in alignment with said aperture for connecting said sections, a shaft rotatably mounted transversely of said casing and extending through said aperture and said opening, a' fan mounted on said shaft in said inlet aperture, a fan mounted on said shaft in said openmg, and means for driving said shaft and rotor.

5. In steam boiler plants, the combination tween said channels and said mass and means for conducting the flue gases past the regenerative material through the central opening in said annular mass.

6. In steam boiler plants, the combination with a boiler, a channel for air passing to said boiler, a channel for flue gases passing from said boiler, a regenerative air preheater comprising a rotor containing'regen- 'erative material provided with passages through the same for air and flue gases and arranged to rotate within sa d channels, a central channel in said rotor and means for conducting the flue gases past the regenerative material of the rotor through said central channel. v

7. In steam boiler plants, the combination with a boiler and a stack provided with a channel for air and a channel for flue gases,

of a regenerative air preheater comprising a rotor containing a solid regenerative material, which is provided with passages through the same for the air andflue gases, said rotor being arranged to rotate about a vertical axis within the said channels of the stack, and provided with a central channel. and means for conducting the flue gases past the regenerative material of the rotor through said central channel.

8. In steam boiler plants, the combination with a boiler and a stack, of a regenerative air preheater comprising a rotor containing a solid regenerativematerial which is provided with passages through the same for the air and flue gases, said rotor being arranged to rotate about a vertical axis within the said stack and provided with a central channel, the stack being divided into 'two channels for flue gases and one channel for air, the one of the channels for flue gases communicating with the regenerative material of the rotor, whereas the second channel for flue gases communicates with the central channel through therotor, and means for conducting the flue gases past the regenerative material of the rotor through said cen' tral channel.

9. In steam boiler plants, the combination with a boiler and a stack, of a regenerative air preheater comprising a rotor containing a solid regenerative material which is provided with passages through the same for the 'air and flue gases, said rotor being arranged to rotate about a vertical axis within the said '.stack and provided with a central channel,

the stack being divided into two channels for flue gases-and one channel for air, the one of the channels for flue gases communicating with the regenerative material of the rotor, whereas the second channel for flue gases communicates with said central channel through the rotor, means for conducting the flue gases past the regenerative material of the rotor through the central channel, and a fan located above the rotor and forcing the flue gases from the channel communicating with the regenerative material into the chan nel communicating with the central channel through the rotor.

10. In steam boiler plants, the combination witha boiler, a boiler furnace and a stack, a rotor in said stack arranged to rotate about a vertical axis, a central uninterrupted passageway for flue gases through said rotor, a second passageway through said rotor surrounding said central passageway, regenerative material in said secondpassageway, a plurality of passages through said regenerative material, means to conduct air gases from said second passageway to said outlet and means to control the passage of flue gases-through said central passageway and said second passageway.

In witness whereof we have hereunto set our hands.

FREDRIK LJUNGSTROM. NlLS FREDRlK FllJZllllONv ANDERSSON. 

